The present invention relates to a cosmetic makeup and/or care composition for keratin fibers and/or the skin, comprising at least one dispersion of particles comprising an at least partially external phase of supple type based on supple polymer, and an at least partially internal phase of rigid type that is a crystalline or semi-crystalline functionality material. More especially, the invention relates to the use of at least one particle disperesion comprising an at least partially external phase based on supple polymer, and an at least partially internal phase of rigid type that is a crystalline or semi-crystalline functionality material, in a cosmetic composition for improving the staying power and level of comfort of a deposit of the said composition, applied to the keratin materials.
The introduction of film-forming compounds into cosmetic compositions, as described, for example, in EP-A-0 775 483, as a dispersion in an aqueous phase, makes it possible to increase the staying power of the products, but often to the detriment of the level of comfort, and usually in a manner that is unacceptable to users. These problems of the level of comfort are partly associated with the mechanical properties of the deposits obtained on the skin. Specifically, cosmetic compositions containing film-forming compounds often create, when they dry on the skin, sensations of tautness that users find unpleasant. Furthermore, it may arise that the intrinsic rigidity of the film-forming compounds, when the film is formed on the skin, is too large, thus giving an unpleasant mask sensation during movements, for example of the face. In the case of dispersions in a non-aqueous medium, patent application EP-A-0 987 012 describes an improvement in that, to improve the transfer-resistance cosmetic properties relative to the compositions of patent application EP-A-0 749 747, the polymer particles were surface-stabilized in dispersion by means of a stabilizer that may be a block polymer, a polymer grafted with pendant chains or a random polymer, alone or as a mixture. However, the stabilizer is found in solution during storage of the composition in the jar or during use, which poses problems of homogeneity and thus of stability of the compositions comprising it.
Moreover, if the stayin power of the film is promoted, by using a film-forming compound that forms a particularly supple film, there is an appreciable risk of the cosmetic composition containing such a film-forming agent becoming sticky, and thus difficult to use cosmetically, for example due to the appearance of a phenomenon of surface bonding when applied to the skin.
There is thus still a need for compositions that combine staying power and a level of comfort, that are stable and that can be applied to the skin or the lips.
One subject of the invention is, precisely, a cosmetic makeup and/or care composition for keratin fibers and/or the skin (including mucous membranes such as the lips), comprising a particle dispersion comprising at least one at least partially external phase of supple type comprising at least one supple polymer, with a glass transition temperature of less than or equal to 60xc2x0 C. and preferably less than or equal to 45xc2x0 C., and at least one at least partially internal phase of rigid type which is functionality crystalline or semi-crystalline material with a melting point of greater than 40xc2x0 C. and preferably greater than 60xc2x0 C., and which is such that the supple polymer is at least partially attached by chemical grafting to the said phase of rigid type.
The expression xe2x80x9cglass transition temperaturexe2x80x9d means the temperature at which the material passes from a solid state to a rubbery state. It is measured by a change in specific heat or a change in volume of the material observed. Differential thermal analysis (known as the DTA method) and differential calorimetry (known as DSC for xe2x80x9cDifferential Scanning Calorimetryxe2x80x9d) are methods for measuring such a glass transition temperature, and give substantially identical results. Thus, the glass transition temperature is an item of data measured, for example, from DSC measurement, according to ASTM standard D3418-97. Furthermore, by defining the polymer by means of a glass transition temperature, this means that the polymer can have heterogeneities in its microstructure but its overall behaviour is close to that of the phase of the polymer that has this glass transition temperature.
Suprisingly, the Applicant has found that the application of such compositions gives a deposit with noteworthy cosmetic properties. In particular, such compositions are comfortable when applied, and stay on remarkably well. They do not show any surface stickiness and have very good mechanical qualities once applied to the skin, after drying. In addition, they are stable i.e. there is no decomposition into two phases relative to each other, with appearance of heterogeneous regions in the packaging or during or after application.
The advantage of such compositions is also that they have properties of absence of migration and of xe2x80x9ctransfer resistancexe2x80x9d. The term xe2x80x9cmigrationxe2x80x9d means an overflowing of the composition beyond the initial mark. Specifically, large migration of cosmetic composition, and in general of the liquid fatty phase that may be present in the said composition, in particular when it is charged with colouring materials, leads to an unattractive effect around the area of application, for example around the lips and the eyes, which particularly accentuates wrinkles and fine lines. The composition according to the invention thus makes it possible to limit, especially in hot and humid regions, the migration of parts of the composition into the wrinkles and fine lines, after it has been deposited on the skin or the lips. Furthermore, the cosmetic composition, especially the makeup or care composition, according to the invention shows virtually no transfer, i.e. it virtually does not come off, leaving marks, on certain supports with which it may be placed in contact, and especially a glass, an item of clothing or the skin. Consequently, the user does not need to regularly freshen the application of the composition, especially a foundation or a lipstick, and does not have to tolerate the appearance of these unacceptable marks, for example on blouse collars.
The invention applies to makeup products for the lips, for instance lip products such as lipsticks and lip pencils. The invention also applies to care and/or treatment products for the face and/or the body, i.e. the skin, including the scalp, and the lips, for instance care products for the human face or body. The invention also applies to makeup products for skin, of both the human face and body, for instance foundations, concealer products, eyeshadows, face powders and temporary tattoo products. Finally, the invention applies to body hygiene products, for instance deodorants, shampoos and conditioners, to makeup products for the eyes, for instance eye liners and pencils, and also to care and makeup products for keratin fibers, for instance the hair, the eyelashes and the eyebrows, such as mascaras.
In one embodiment of the invention, the said particles containing phases of rigid type and of supple type are film-forming, and they can thus form a film generally at about 30xc2x0 C., i.e. they have an MFFT (for xe2x80x9cminimum film-forming temperaturexe2x80x9d) of less than or equal to about 30xc2x0 C. and preferably about 25xc2x0 C.
The formation of a film at room temperature of the particles according to the invention may require the presence of at least one coalescer or at least one plasticizer in the comestic care and/or makeup composition according to the invention, as is known to those skilled in the art. Such a plasticizer is generally a volatile organic compound that remains in the composition during the use and the formation of the film. Such a coalescer is generally a volatile organic compound that evaporates during the use and formation of the film.
According to such an embodiment, the film obtained after drying the composition, generally with spreading for a cosmetic composition, is such that it has a maximum tensile stress (for a percentage of elongation of less than 100%) of less than or equal to about 10 MPa. The maximum tensile stress may be determined during tensile tests as described in ASTM standard D638-99, for example on a dumbbell-shaped test specimen (of type IV according to the standard) at a speed of 50 mm/min. The test specimens are cut out of films about 100 xcexcm thick. According to this standard, to prepare a film, the dispersions are poured into a temperature equal to 25xc2x0 C. in order for the volatile medium to evaporate off, and the film formed is recovered. The tests are preferably preformed on films that have been dried for at least 24 h at room temperature (25xc2x0 C.) and at ambient humidity (50%).
Such a film shows no surface stickiness, i.e. after contact between the finger and the surface of the film, an impression of stickiness of the surface is not experienced when the contact with the said surface is not experienced when the contact with the said surface is broken by removing the finger, which is in contrast with what may be experienced after contact with an adhesive face, for example an adhesive tape.
Preferably, the supple polymer is especially chosen from block and/or random polymers. The expression xe2x80x9cblock and/or random polymersxe2x80x9d means polymers whose monomer distribution on the main chain or the pendant chain units is in block and/or random form. Such polymers may be polyacrylics, polymethacrylics, polysiloxanes and especially polydimethylsiloxanes (PDMS), polyamides, polyurethanes, polyolefins, especially polyisoprenes, polybutadienes and polyisobutylenes (PIB), polyesters, polyvinyl ethers, polyvinylthio ethers and polyoxides, and combinations thereof. The term xe2x80x9ccombinationsxe2x80x9d means coplymers that may be formed from the monomers leading to the formation of said polymers, whether these copolymer are in block or random form.
The phase of rigid type is an organic or mineral material. Such chemical grafting makes it possible, by establishing covalent bonds, to stabilize the link between the phase of rigid type and the phase of supple type.
The term xe2x80x9cfunctionalityxe2x80x9d means that the surface of the crystalline areas in contact with the supple polymer must contain reactive functions in order to create covalent bonds. This may take place in a manner known to those skilled in the art. Examples of reactive fuctions that may be mentioned include acidic or basic functions, for example amine functions, on the mineral surfaces, or reactive double bonds on (semi)crystalline polymers.
The expression xe2x80x9cmelting pointxe2x80x9d means the temperature at which the material phases from a solid state or a liquid or partially gaseoues state. It is reflected by an endothermic peak that may be observed by differential thermal analysis (known as the DTA method) or by differential calorimetry (known as the DSC method, for xe2x80x9cDifferential Scanning Calorimetryxe2x80x9d), which are methods for measuring such a melting point, and which give substantially identical results. Thus, the melting point is an item of data measured, for example, from DSC measurement, according to ASTM standard E794-98. In the case of mineral materials, the measurement takes place in a DTA cell of high specific temperature. Furthermore, by defining the material by means of a melting point, this means that the material by behaviour is close to that of a material having this melting point.
The particles are generally from 1 nm to 10 xcexcm in size and preferably from 10 nm to 1 xcexcm in size, measured, for example, by a machine of Brookhaven BI-90 type which uses the technique of light scattering.
The proportion of phase of supple type relative to the phase of rigid type in the particles according to the invention is generally such that the phase of supple type represents at least 1%, preferably at least 5% and even more preferably at least 10%, or even 25%, and up to 99.999%, by volume relative to the total volume of the particle.
In any case, the phase of rigid type and the phase of supple type are incompatible, i.e. they may be distinguished using techniques that are well known to those skilled in the art, such as, for example, electron microscopy.
The morphologies of the phase within the dispersed particles may be, for example, of core-shell type, with shell portions entirely surrounding the core, but also core-shell with a plurality of cores, or an interpenetrating network of phases. What is essential is that the phase of rigid type is at least partly and preferably predominantly external.